Heating apparatus for caravans and the like

ABSTRACT

A portable heater particularly for caravans forming a thermogenerator comprises a casing containing a substantially flat plate thermoelectric element heated by an inverted gas burner tube, the air being circulated by a fan from the bottom of the casing onto the underside of the base of the heating element, around the element and over the outside of the burner tube which forms a heat exchanger and is then distributed onto the room to be heated, means being provided for regulating the heat passing to the room and for charging a battery to supply electric current for lighting room.

United States Patent Inventor Michel Vial Rhone, France Appl. No. 880,623 Filed Nov. 28, 1969 Patented Nov. 16, I97] Assignee Application de Gaz Paris, France Priority Nov. 29. 1968 France 50,695

HEATING APPARATUS FOR CARAVANS AND THE LIKE Primary Examiner-Charles J. Myhre Attorney-Alexander & Dowell ABSTRACT: A portable heater particularly for caravans forming a thermogenerator comprises a casing containing a substantially flat plate thermoelectric element heated by an inverted gas burner tube, the air being circulated by a fan from the bottom of the casing onto the underside of the base of the heating element, around the element and over the outside of the burner tube which forms a heat exchanger and is then distributed onto the room to be heated, means being provided for regulating the heat passing to the room and for charging a battery to supply electric current for lighting room.

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SHEET 1 BF 2 V, LiVZENTOR.

HEATING APPARATUS FOR CARAVANS AND THE LIKE This invention relates to improvements in heating apparatus forming an electric thermogenerator.

The apparatus is heated by gas and in particular butane or propane gas liquified under pressure and stored in a transportable tank and is particularly suitable to be used for camping; caravans and similar applications.

It is known that the practice of camping by means of a motor vehicle presents the double problem of heating and the supply of electric energy. Numerous stoves have been thought of operating with liquified gas and made in a form which is light and at the same time taking up little space. Such systems resolve the problem of heating in the practice of camping or in similar circumstances. On the other hand the electric energy necessary for lighting only can be provided at low voltage by connecting up to the accumulator batteries of the motor vehicle connected to a camping caravan but as this battery has only a limited capacity its regular recharging is indispensable which normally makes it necessary to run the motor of the vehicle idle if this latter is not used regularly. There has also been the idea of combining with the heating apparatus thermoelectric generator elements which supply the energy necessary for this recharge and which even permits of providing for the supply of energy to a battery separate from that of the aforementioned vehicle.

The invention aims at permitting the making of such a combined heating and electric energy-producing apparatus which has a high output, of flexible use and which lends itself particularly well suited to being installed aboard a camping caravan.

The invention also aims at realizing such an apparatus which permits of recharging conventional l2-volt batteries by using for this purpose only a single thermoelectric generator element of known type giving a voltage of the order of 6 to 7 volts only.

The apparatus made in accordance with the invention is characterized in that the base of its hearth is constituted by the hot surface of a flat thermoelectric element heated by an inverted gas burner and that the whole of this hearth is mounted inside a casing into whichair penetrates through the bottom of cooling first of all the lower outer face of the base of the hearth, that is to say the cold face of the thermoelement and to then ascend by convection currents continuing to be heated by contact with the lateral outer surface and possibly the upper surface of the hearth before leaving this enclosure through the top from whence it may be distributed into a room to be heated.

According to a preferred embodiment the upper part of the hearth is made as a heat exchanger carrying on its inner and outer faces vanes which extend in vertical planes.

The casing of the apparatus contains advantageously an axial fan mounted under the hearth in the axis of the latter.

It is convenient to make in the upper part of the casing at least two openings one communicating with a room to be heated and the other communicating with the outside and to control them by a shutter allowing for controlling one of these openings by more or less closing the other.

In a preferred embodiment the lower part of the casing encloses a thermostat for control of the burner as well as all the ignition and regulating devices.

The invention will be described with reference to the accompanying drawings:

FIG. I is a general vertical section of an apparatus according to the invention;

FIG. 2 is a detail section enlarged on line II-II (FIG. I) of the head of the burner of this apparatus;

FIG. 3 is a schematic diagram of the various devices of the apparatus;

FIG. 4 is a development of the starting control cam;

FIG. 5 shows a diagram of the electrical connections.

The apparatus shown in FIG. 1 comprises a casing 1, for example, of aluminum the inside of which is divided in the vertical direction into three parts or zones which have been given the references A, B and C respectively. The lower zone A is defined in height by a horizontal partition 2 perforated with a circular central opening 20 of large diameter surrounded by a cylindrical flange or skirting 2b directed downwards. The partition 2 is integral with arms 3 which support an electric motor 4 having a vertical axis. On the upper end of the shaft of this motor is mounted a fan 5 which rotates at a reduced speed inside the skirting 2b so as to blow from the bottom upwards. In this zone A the wall of the casing 1 is perforated by numerous openings Ia forming air inlets for the fan. It will also be noted that the zone A encloses a regulator assembly b, a thermostat 7 and a control unit 8 all as hereinafter described.

The zone B of the inner space of the casing 1 encloses a thermoelectric element or module 9 of flat shape and circular in the example shown. Such elements being well known in practice a detailed description will not be given. It will simply be noted that the one shown comprises two plates and 9b between which are interposed cells 9c each of which constitutes a thermoelectric couple these cells being mounted in series with their hot and cold seams in thermal connection respectively with the upper and lower plates 90 and 9b. The lower plate 9b is integral with radial vanes 10 disposed so as to fomi with the aforementioned plate a radiator adapted to receive the air current blown by the fan 5 while the upper plate 9a is fixed against the lower open end of the hearth the lower part of which is constituted by an inverted cylindrical box 11.

The upper part of the hearth constitutes a heat exchanger comprising, affixed to the box 11, a hollow cylindrical body 12 the upper end of which is closed, this body being integral with a lateral discharge tube 13 which is engaged in a radial tube lb leaving the casing l laterally.

Axially through the hearth there extends an inverted gas burner comprising a vertical biconical pipe 14 integral with the upper face of the body 12 and adapted to form a venture discharge for this pipe being connected to a central opening provided in the upper base of the box 11. This base is in its turn integral with a conical truncated chamber 15 wide mouthed at the bottom and the large base of which is constituted by a perforated plate 16 while its smaller upper end is connected to the pipe 14.

The body 12 of the heat exchanger carries radial vanes I7 and 18 respectively on its outer surface and on its inner surface. It will also be noted that the base of the box II is per forated with openings Ila in its annular part which surrounds the small base of the conical truncated chamber IS.

The upper zone C of the inner space of the body I encloses an axial head 19 the detail of which is as follows: This head 19 receives the gas through a main piping 20 and distributes it to a tube 21 directed downwards into the throat of the venturi 14. The head 19 is in addition integral with a plate 19a which forms a cover of an upper cylindrical part connecting with the inlet of the venturi 14. The chamber defined by the cylindrical part 140 communicates with the outside through an air inlet tube 22 which extends radially beyond the wall of the body I.

The upper zone C encloses a transverse spindle 23 on which is mounted a rocking switch shutter 24. This latter of rectangular shape has on its two sides parallel to the spindle 23 sealing pads 24a capable of bearing respectively against the upper horizontal wall of the casing l or against a horizontal flange 25 located in the plane of separation of the zones B and C. The operation of this shutter 24 may be ensured by a button 26 hinged to one of the pads 24a and passing through a slot (not shown) provided in the wall of the casing I.

In the aforementioned zone C the vertical walls parallel to the spindle 23, air outlet openings are made constituted by groups of openings 10 and Id respectively. The apparatus is normally intended to be placed against the wall 27 of the area to be heated (for example a caravan). This wall is perforated by an opening 27a against which the wall of the casing I is ap' plied which has the openings Id. Against the outer face of the wall 27 there is disposed a plate 28 comprising a system of venetian blind slats 28a to the right of the opening 27a. This plate 28 is connected by crossmembers 29 to another plate 30 which defines with the crossmember a hot air distribution space D into which opens the air inlet tube 22. The tubing 1b aforementioned connects with the plate 30. The plate 30 is connected in its turn by the crossmembers 31 to a third plate 32 disposed opposite the outlet of the tubing aforementioned making an intermediate space E which constitutes the smoke outlet chamber as will be better understood from the following description. The general operation is as follows:

The gas which escapes downwards from the pipe 21 draws into the venturi 14 air brought from outside through the chamber D and the tube 22. The mixture thus arrives in the truncated conical chamber 15 and passes through the perforated wall 16 to burn inside the casing 11 so that the flame licks the upper plate 9a of the thennoelectric element 9 thus keeping it at a relatively high temperature. The hot gases ascent again through the perforation 11 of the bottom of the casing 11 then into the body 12 and escape outside through the tube 111 and the chamber E which forms a screen.

At the same time the fan provides an ascending current of cold air which circulates in contact with the heat exchanger constituted by the vanes cooling these latter and therefore keeping the lower plate 9b of the thermoelectric element 9 relatively cold. The air which leaves the vanes 10 mounts into the zone B and passes in contact with the vanes 17 absorbing the heat which these latter receive from the body 12 and the inner vanes 18 of the latter.

It will be understood in fact that the assembly 18-12-17 of the upper part of the hearth constitutes a heat exchanger between the hot gases which ascend from the casing 11 and the air which, in its turn, likewise rises in the annular space between the body and the wall of the casing l. The air thusheated arrives into the upper zone C of the casing and according to the position given to the switch shutter 24 is delivered either inside the caravan through the openings 10 or outside the latter through the openings 1a of the chamber D which constitutes a protection against the influence of any outside draught. It will be understood that in the first case the apparatus ensures the heating of the caravan at the same time as the production of electrical energy as hereinafter described (cold weather conditions) while in the second case it supplies only this energy without heating the room as is described in hot weather. There is of course nothing to prevent placing the shutter 24 in an intermediate position.

There remains to explain the lighting and regulating devices of the apparatus as well as the diagram of electrical connections. It will be convenient to describe first of all the detail of the head 19 hereinbefore mentioned. As FIG. 2 shows the head comprises a solid body with a main entry 1% disposed laterally and which discharges into a vertical channel 19c connected to the pipe 21. The body 19 also has an auxiliary inlet 19d which discharges into an annular bore 19c surrounding the pipe 21. This bore is extended downwards by a sleeve 33 which terminates a little above the end of the pipe 21. A connection 34 joins the auxiliary inlet 19d to piping 3S intended to supply gas to the sleeve 33 with a view to enriching the mixture at the time of igniting the burner.

FIG. 3 shows the general operation of the apparatus.

The fan 5 brings air to the vanes that is to say, to the cooling radiator of the thermoelectric element 9. The air leaving the vanes 10 arrives at the heat exchanger constituted by the assembly 18-12-17 and leaves in a heated state in the zone C to escape as desired either to the inside through the openings 1c or outside through the openings 14'. The outside air sucked through the tube 22 arrives at the burner 14 which supplies the heat to the thermoelectric element 9 by discharging its burnt gases into the exchanger 18-12-17 from which they pass through the chamber E to the outside of the caravan. The combustible gas coming from a cylinder, not shown, arrives at the regulating device 36. It passes from there through a general tap 37, a safety valve 38 (of the type held open by an electromagnet against a drawback spring) then an electromagnetic valve 39 into the main inlet 1% of the head of the burner. It will be noted that there is provided a bypass piping 450 in parallel with the valve 39 this piping having a calibrated opening 41 shown in the diagram (FIG. 3) and provided so as to pennit a pilot operation of the burner when the valve 39 is closed.

The piping 35 of FIG. 3 leaves the main piping before the valve 39 to supply the inlet 19d. It is controlled by a valve 42.

Connected to the burner 14 is a thermoelectric couple 43 which feeds an electric holding magnet of the safety valve 38 to keep this latter open when the flame has been ignited. The electric diagram (which will be given in detail later) comprises the battery F divided into two halves of 6 volts each. From the thermoelectric generator 9 the current passes through a first working control relay 44 (voltanetric relay) to which is connected a lamp 45. The current arrives at a switch assembly 46, passes through a load control relay 47 to which is connected a second lamp 48 then to a general interruptor 49 and to the midpoint of the battery F. A current shunt feeds the thermostat 7 which controls the valve 39. Connected to the burner 14 is an ignition filament 50 (FIGS. 1 and 3) which can be controlled by means of a switch 51 (FIG. 4).

On the electric cable (FIG. 3) which connects the thermoelectric couple 43 for the safety valve 38 is inserted a biplate switch 10a intended to cut the circuit in the event of a premature stopping of the fan causing the vanes 10 (and consequently also the lower plate 9b of the element 9) to become over heated.

The general control is effected by the unit 8 of FIG. I to which are connected two cylindrical rotary knobs 52 and 53 respectively. The central knob 52 operates the needle of the general tap 37. One must therefore operate it to open the top before starting and close it again when it is desired to stop the apparatus. The second knob 53 causes a cam to rotate the development of which has been diagrammatically shown in FIG. 4. As can be seen an arm 54 has three bosses 54a, 54b and 540. The first controls the valve 42 for enriching at the time of the ignition, the second leads to the opening the safety valve 38 against the spring which brings it back to closing finally and the third acts on the switch 51 to close it. It will be understood that if the general tap is open when the cam 54 is operated the gas is brought to the apparatus at the same time as the current is caused to pass through the filament 50. The gas therefore arrives simultaneously at the pipe 21 and to the sleeve 33 thus determining the formation of a very rich mixture which ignites on contact with the filament without causing any flame return and which heats the thermocouple 43. At the end of some tens of seconds this latter feeds into the electromagnet of the valve 38 a current sufficient to keep this latter in the open position. The cam 54 may therefore be brought back towards its resting position which puts out of action the ignition filament and couples the additional admission of gas through the sleeve 33 bringing back the full richness of the mixture in the burner to its normal value.

From this moment the burner operates at full working condition assuming that the battery is fully charged and that the thermostat 7 is in the cold position for which the valve 39 is open. It will be seen later on what happens with the electric circuits. When the thermostat 7 comes to the hot position it closes the valve 39 so the burner is only fed with gas through the calibrated opening 41 and operates due to this at slowed speed.

It will be understood that by placing the thermostat 7 in the bottom of the casing 1, as shown in FIG. 1 it is caused to act as an environment regulator since it detects the temperature of the air drawn into the room. It therefore regulates the heating of the latter in the manner desired if one is in the cold period and when the battery is completely charged which will all be seen later.

In the case of stopping the fan 5 the vanes 10 become heated and the biplate switch cuts the circuit of the thermo couple thus causing the closing of the safety valve 38.

H6. 5 indicates the detail of the electric circuits diagram and permits better understanding of the indications of FIG. 3. As indicated above the battery F, assumed to be 12 volts is divided into two halves F 1, F2 of 6 volts each. A double switch 460 permits of connecting alternatively one then the other of 5 these two half batteries to a line comprising two conductors 55 and 56. The conductor 55 is connected to the positive pole of the thermogenerator 9 by means of a diode 57 which prevents the battery from discharging on the generator when this latter is at rest. In its turn the conductor 56 is connected to the negative pole of the generator by a movable charge control contact 47a controlled by the winding of the relay 47 of FIG. 3. At the charge end (position of the movable parts in broken lines) this contact connects the negative pole aforementioned to a resistance 58 as will be explained later.

The winding 47 is connected to a conductor 59 which is connected to the negative pole of the battery F. its other end is connected to another conductor 60 adapted to be connected in its turn to the positive pole of the battery F by the movable contact 44a of the voltametric relay 44. At rest (position in broken lines) this movable contact 44a connects the positive pole to the lamp 45 the circuit of which is closed on the conductor 59. The conductor 60 is connected by a movable contact 47b of the relay 47 to a circuit comprising in series the thermostat 7 are the winding of the electrovalve 39 connected to the conductor 59, the lamp 48 being mounted in parallel across the assembly of this winding 39 and of the thermostat 7. Between the two conductors 59 and 60 there is mounted the switch device 46 which comprises a time base of relatively long period and an electromagnet for control of the switch 46a.

Between the positive pole and the negative pole of the battery are mounted in series one with the other the ignition filament 50 and its control switch 51.

There will be seen at 49 the general bipolar switch interposed between the poles themselves of the battery and the circuits just described.

Before explaining the operation of the electric circuits the object assigned to them should be noted. it has been admitted that the essential role imparted to the apparatus consists in keeping the battery F charged even if that entails an excess of heating which can be easily remedied by means of the valve 24. It is therefore considered that the reduced working condition of the burner must only occur once the battery is fully charged.

This being granted the operation is as follows:

At rest the contact 47a connects the generator 9 to the conductor 56. The contact 47b is opened thus insulating the electrovalve 39 which is arranged to be normally in the open position. The contact 44a is on the lamp 45. If the general switch 49 is closed the lamp ignites the signal that the battery is in, c rcuit but is not on charge. The lamp 48 remains on the contrary extinguished indicating that the thermostat is out of action.

As soon as the generator 9 reaches a sufficient voltage (a little more than 6 volts) the voltametric relay 44 comes into operation displacing the contact Me which connects the conductor 60 to the positive pole of the battery. That has the effect of closing the valve 45 and putting in circuit the winding of the charge control relay 47. if it is assumed that the battery is not completely charged, this relay 47 does not operate so that the thermostat 7 remains out of circuit and the valve 39 remains in the fully opened position. The burner therefore continues to work at maximum working conditions but the thermogenerator 9 may commence to act through the diode 57 to charge that of the two half batteries F1 and F2 which are then in circuit. Simultaneously the switch device 46 comes into play to actuate periodically the switch 46a so that the charge current coming from the generator 9 is sent altematively to the half-battery Fl then to the half-battery F2. There is thus obtained a regular charge of a 12-volt battery with a single thermogenerator of only 6 volts.

When the battery F is completely charged, that is to say, when both of its two-halves F l and F2 have reached a voltage limited to the order of 7% the relay 47 is put in operation displacing its two movable contacts 47a and 47b. The displacement of the contact 470 has the effect of stopping the the charging of the battery while maintaining the output of the generator 9 the current from which circulates through the resistance 58. The contact 47b puts in circuit the thermostat 7 and the winding of the electrovalve 39 igniting simultaneously the lamp 48 which indicates the end of charging.

As long as the battery is fully charged and thermostat Tinay intervene to close the circuit of the winding of the electrovalve 39 and thus to cause the closing of this latter, the burner then operating on a reduced supply as explained above (that is to say by feeding through the calibrated opening 41 of the H0. 3). This reduced working reduces the consumption of combustible gas to the minimum required to maintain at a suffrcient temperature the hot plate 9a (FIG. 1) of the thermogenerator element or module 9 consequently avoiding in the latter abrupt surges in temperature liable to bring about its premature aging.

It is easy to verify the above described circuits ensure the complete safety of the automatic operation of the whole of the apparatus and that they guarantee that the battery always remains charged to a maximum.

lclaim:

ll. An electric thermogenerator comprising:

a flat thermoelectric unit having a cold side and a hot side, said thermoelectric unit being disposed substantially horizontally with its cold side facing downwardly and with its hot side facing upwardly;

heating means to heat the upper hot side of said thermoelectric unit;

and a fan to supply cold air to the lower cold side of said thermoelectric unit to cool same.

2. In an electric thermogenerator as claimed in claim I, said heating means being in the form of an inverted gas burner disposed above said thermoelectric unit.

3. In an electric thermogenerator as claimed in claim 1, vanes extending downwardly from the lower cold side of said thermoelectric unit in heat-exchange relation with cold air supplied by said fan.

4. In an electric thermogenerator as claimed in claim 3, said fan having a vertical axis, and said vanes being disposed substantially radially with respect to said axis.

5. In an electric thermogenerator as claimed in claim 2:

a substantially vertical burner casing surrounding said inverted gas burner and extending downwardly to engage the upper hot side of said thermoelectric unit in such manner as to define a hearth with said hot side forming the lower wall of said hearth;

means to supply combustible gas and. combustion air to said inverted burner;

and exhaust means for the combustion gases generated by said inverted burner within said burner casing.

6. A combined heating and electricity-generating apparatus comprising:

a substantially vertical outer casing having a lower air inlet and an upper air outlet;

a flat thennoelectric unit having a hot side, a cold side and an outer edge, said thermoelectric unit being disposed substantially horizontally within said outer casing above said lower air inlet and below said upper air outlet with said hot side facing upwardly, with said cold side facing downwardly and with said outer edge being spaced from said outer casing so as to leave a. first annular passage between said edge and said casing;

a fan disposed within said outer casing below said thermoelectric unit to blow against said cold side thereof an air stream drawn through said lower air inlet, said air stream thereafter escaping upwardly through said first annular passage;

an inverted gas burner disposed within said casing above said thermoelectric unit to heat the upper hot side thereof;

a burner casing surrounding said inverted gas burner within said outer casing, said burner casing having substantially vertical lateral walls and extending downwardly to engage the upper hot side of said thermoelectric unit in such manner as to define a hearth with said hot side forming the lower wall of said hearth, said burner casing being spaced from said outer casing so as to leave a second annular passage for the air stream flowing upwardly from said first annular passage;

means to supply combustible gas and combustion air to said inverted gas burner;

exhaust means to discharge outside of said outer casing combustion gases generated by said inverted burner within said burner casing;

and vane means in said hearth and in said second annular passage to transfer heat from said burner casing to said air stream flowing through said second annular passage before said air stream issues from said outer casing through the upper air outlet thereof.

7. In an apparatus as claimed in claim 6, vanes extending downwardly from the lower cold side of said thermoelectric unit in heat-exchange relation with cold air supplied by said fan.

8. In an apparatus as claimed in claim 7, said fan being situated below said vanes and having a substantially vertical axis, and said vanes being disposed substantially radially with respect to said axis.

9. In an apparatus as claimed in claim 6:

a substantially horizontal air conduit to supply air to said inverted gas burner from the outside of said outer casing;

a flat vertical air chamber exterior to said outer casing and in which said air conduit opens, said chamber being open laterally;

and said exhaust means being in the form of a substantially horizontal gas conduit disposed below said air conduit and substantially parallel thereto, said gas conduit passing through said air chamber to open beyond same.

10. A combined heating apparatus and electric thermogenerator comprising:

an outer casing having a lower air inlet and an upper air outlet, with said outlet comprising first and second air passage means;

a thermoelectric unit disposed within said casing with said unit having a hot side and a cold side;

burner means within said casing to heat the hot side of said thermoelectric unit;

means to discharge outside of said casing combustion gases from said burner means;

means to cause an air stream drawn from the lower air inlet of said casing to cool the cold side of said thermoelectric unit and to exhaust through the upper air outlet of said casing;

and two-way valve means within said casing to direct said air stream towards said first air passage means or towards said second air passage means.

11. In an apparatus as claimed in claim 10, heat transfer vane means between the combustion gases of said burner means and said air stream.

12. In an apparatus as claimed in claim 10, disposed in a room, conduit means connecting said first air passage means with the outside of said room, while said second air passage means open directly into said room, whereby said air stream may be discharged either into said room to heat same, or outside of said room when same is not to be heated.

13. In an apparatus as claimed in claim 18:

said casing having an upper portion of rectangular inner cross section with an upper side and four lateral sides; said burner means tenninating short of said upper portion; said first air passage means comprising at least one perforation in a first one of said lateral sides of said upper portion substantially above said burner means; said second air passage means comprising at least one perforation in a second lateral side of said upper portion substantially above said burner means, with said second lateral side being opposed to said first lateral side;

and said two-way valve means comprising a substantially rectangular rocking switch shutter having substantially the same dimensions as the inner cross section of the upper portion of said casing and means to pivot said shutter about an axis parallel to said first and second lateral sides. 

1. An electric thermogenerator comprising: a flat thermoelectric unit having a cold side and a hot side, said thermoelectric unit being disposed substantially horizontally with its cold side facing downwardly and with its hot side facing upwardly; heating means to heat the upper hot side of said thermoelectric unit; and a fan to supply cold air to the lower cold side of said thermoelectric unit to cool same.
 2. In an electric thermogenerator as claimed in claim 1, said heating means being in the form of an inverted gas burner disposed above said thermoelectric unit.
 3. In an electric thermogenerator as claimed in claim 1, vanes extending downwardly from the lower cold side of said thermoelectric unit in heat-exchange relation with cold air supplied by said fan.
 4. In an electric thermogenerator as claimed in claim 3, said fan having a vertical axis, and said vanes being disposed substantially radially with respect to said axis.
 5. In an electric thermogenerator as claimed in claim 2: a substantially vertical burner casing surrounding said inverted gas burner and extending downwardly to engage the upper hot side of said thermoelectric unit in such manner as to define a hearth with said hot side forming the lower wall of said hearth; means to supply combustible gas and combustion air to said inverted burner; and exhaust means for the combustion gases generated by said inverted burner within said burner casing.
 6. A combined heating and electricity-generating apparatus comprising: a substantially vertical outer casing having a lower air inlet and an upper air outlet; a flat thermoelectric unit having a hot side, a cold side and an outer edge, said thermoelectric unit being disposed substantially horizontally within said outer casing above said lower air inlet and below said upper air outlet with said hot side facing upwardly, with said cold side facing downwardly and with said outer edge being spaced from said outer casing so as to leave a first annular passage between said edge and said casing; a fan disposed within said outer casing below said thermoelectric unit to blow against said cold side thereof an air stream drawn through said lower air inlet, said air stream thereafter escaping upwardly through said first annular passage; an inverted gas burner disposed within said casing above said thermoelectric unit to heat the upper hot side thereof; a burner casing surrounding said inverted gas burner within said outer casing, said burner casing having substantially vertical lateral walls and extending downwardly to engage the upper hot side of said thermoelectric unit in such manner as to define a hearth with said hot side forming the lower wall of said hearth, said burner casing being spaced from said outer casing so as to leave a second annular passage for the air stream flowing upwardly from said first annular passage; means to supply combustible gas and combustion air to said inverted gas burner; exhaust means to discharge outside of said outer casing combustion gases generated by said inverted burner within said burner casing; and vane means in said hearth and in said second annular passage to transfer heat from said burner casing to said air stream flowing through said second annular passage before said air stream issues from said outer casing through the upper air outlet thereof.
 7. In an apparatus as claimed in claim 6, vanes extending downwardly from the lower cold side of said thermoelectric unit in heat-exchange relation with cold air supplied by said fan.
 8. In an apparatus as claimed in claim 7, said fan being situated below said vanes and having a substantially vertical axis, and said vanes being disposed substantially radially with respect to said axis.
 9. In an apparatus as claimed in claim 6: a substantially horizontal air conduiT to supply air to said inverted gas burner from the outside of said outer casing; a flat vertical air chamber exterior to said outer casing and in which said air conduit opens, said chamber being open laterally; and said exhaust means being in the form of a substantially horizontal gas conduit disposed below said air conduit and substantially parallel thereto, said gas conduit passing through said air chamber to open beyond same.
 10. A combined heating apparatus and electric thermogenerator comprising: an outer casing having a lower air inlet and an upper air outlet, with said outlet comprising first and second air passage means; a thermoelectric unit disposed within said casing with said unit having a hot side and a cold side; burner means within said casing to heat the hot side of said thermoelectric unit; means to discharge outside of said casing combustion gases from said burner means; means to cause an air stream drawn from the lower air inlet of said casing to cool the cold side of said thermoelectric unit and to exhaust through the upper air outlet of said casing; and two-way valve means within said casing to direct said air stream towards said first air passage means or towards said second air passage means.
 11. In an apparatus as claimed in claim 10, heat transfer vane means between the combustion gases of said burner means and said air stream.
 12. In an apparatus as claimed in claim 10, disposed in a room, conduit means connecting said first air passage means with the outside of said room, while said second air passage means open directly into said room, whereby said air stream may be discharged either into said room to heat same, or outside of said room when same is not to be heated.
 13. In an apparatus as claimed in claim 18: said casing having an upper portion of rectangular inner cross section with an upper side and four lateral sides; said burner means terminating short of said upper portion; said first air passage means comprising at least one perforation in a first one of said lateral sides of said upper portion substantially above said burner means; said second air passage means comprising at least one perforation in a second lateral side of said upper portion substantially above said burner means, with said second lateral side being opposed to said first lateral side; and said two-way valve means comprising a substantially rectangular rocking switch shutter having substantially the same dimensions as the inner cross section of the upper portion of said casing, and means to pivot said shutter about an axis parallel to said first and second lateral sides. 